I love colour tools
Designing for a firm that uses a very limited colour pallet makes you really appreciate designing with new colours. I love kuler, Kuler is also available as an air app that links with your kuler account to bring your colour favorites and kuler to the desktop. I also use Art Directors Tool Kit by Code Line Communications. Below is a link to a great list of other colour tools.
21 Stimulating Color Palette Tools For Designers [sitepoint]
